ADESCRIPTION (provided by applicant): The broad goal of this proposal is to determine the safety and efficacy of rhPRL for lactation insufficiency in mothers of premature infants. Breast milk is the nutrition of choice for infants based on the nutritional, medical and psychological advantages for both the infant and the mother. In premature infants, breast milk provides further advantages over formula including better digestion and nutrient absorption, faster progression of feeding, a decreased rate of infection and infection severity, improved visual function and neurodevelopment and a decreased rate of necrotizing enterocolitis. Mothers of premature infants have to pump to maintain their milk supply while infants are too small or weak to suckle. The milk supply diminishes and lactation insufficiency develops in up to 50% of mothers by the fourth week of pumping. The prevalence of lactation insufficiency in mothers of premature infants is estimated to be 66,000. There is evidence that lactation insufficiency is related to low prolactin levels and that increasing prolactin increases milk volume. Unfortunately, there is only one medication available for treatment of lactation insufficiency in the United States; however, it is not FDA approved and it has side effects including debilitating depression that limit its use. In this proposal, the safety and efficacy of r-hPRL will be examined in mothers who develop lactation insufficiency while pumping to maintain their milk supply for a premature infant. R-hPRL will be administered for 7 days, either once or twice daily. Prolactin levels and milk volume will be compared in the daily r-hPRL, twice daily r-hPRL and placebo treated subjects during treatment and 1 week after study completion. Milk composition will also be compared in r-hPRL and placebo treated groups. Acceptability of the treatment and side effects for both mother and infant will be documented. Finally, breast-feeding rates and infant growth will be assessed during a 1 year follow-up. This Phase 2 study will be the first to examine the use of r-hPRL for lactation induction and is expected to provide the critical backdrop for the development of r-hPRL as a treatment for lactation insufficiency. The studies may thus provide data that lead to the first FDA approved treatment for lactation insufficiency. In addition, these studies may further define the physiological role of prolactin in lactation.